This is the 18489th most frequent Russian word.
яичниках
"Ovaries."
Here, 'яичниках' refers to the ovaries as a biological organ where a natural physiological process occurs.
В яичниках происходит созревание яйцеклеток.
In the ovaries, the maturation of eggs takes place.
In this context, 'яичниках' is used to specify the location of health-related findings.
В ее яичниках обнаружились кисты.
Cysts were found in her ovaries.
Here, 'яичниках' pertains to anatomical terminology relating to the biological system of an organism.